The recovery of residual oil from oil-bearing subterranean formations by flooding of the formation with an aqueous medium containing a polymer such as a partially hydrolyzed polyacrylamide has received widespread attention as evidenced by the substantial number of U.S. patents directed to the preparation and use of such solutions. Included among this large group of patents are U.S. Pat. Nos. 2,827,964, 3,002,960, 3,039,529, 3,370,649, 3,558,759, 3,800,877, 3,825,067, 3,841,401, and 3,853,802. At least one of the aforementioned patents, namely, U.S. Pat. No. 3,370,649, suggests the preparation and injection of an aqueous solution of a partially hydrolyzed polyacrylamide at the site of the oil-bearing formation. In accordance with the teaching of that patent, polymerization and hydrolysis are carried out simultaneously in the presence of an alkali metal polyphosphate and a suitable catalyst for a time sufficient to effect hydrolysis of from 5 to about 70 percent of the amide groups of the polymer. The resulting aqueous solution of the partially hydrolyzed polyacrylamide is then mixed with water, and injected into an input well penetrating a subterranean oil-bearing formation, and forced through the formation in the direction of one or more output wells also penetrating the formation. The random, haphazard, all-in-one-pot production approach disclosed in the patent not only is inefficient and wasteful, and, therefore, economically unfeasible, but, also, and perhaps more importantly, yields an end product having properties which are unpredictable, and which, except by fortuitous happenstance, are incapable of meeting the specific permeability requirements of a subterranean oil-bearing formation of interest. More specifically in this latter connection, the process of U.S. Pat. No. 3,370,649 does not enable the controlled production of an aqueous solution of a polymer for use in an oil-bearing formation having the necessary injectivity and mobility properties both at the input well to prevent, or substantially reduce, wellbore plugging, and, away from the input well, that is, the matrix, to enable adequate displacement of oil in the formation in the direction of an output well to take place. Nor, moreover, does U.S. Pat. No. 3,370,649, or any of the other aforementioned U.S. patents for that matter, suggest a system or process for accomplishing such a result.